Self-propelled combine harvesters comprise a chassis that is supported on the ground by front, driven wheels (or track drive mechanisms) and rear, steerable wheels. A feederhouse assembly, at the front end of which a harvester head is in turn mounted, is arranged on the front side of the combine harvester. The harvester head can be designed, for example, as a cutting mechanism having a mower bar and a reel arranged thereabove or a transverse conveying auger or a transverse conveyor belt, or it can be designed as a corn picker having picking units and a transverse conveying auger. During harvesting, the harvester head conveys the cut-off or taken-up crop through a rearward discharge opening onto the feederhouse assembly, which in turn conveys it into the interior of the combine harvester, where it is threshed, separated and cleaned.
The feederhouse assembly comprises a housing, in which a chain conveyor, typically operating in an undershot manner, circulates about an upper and a lower feederhouse roller, which are mounted in the housing. The lower feederhouse roller is arranged to the rear of the discharge opening of the harvester head, and the upper feederhouse roller, which cooperates with the chains of the chain conveyor by means of pinions, transfers the crop to an (axial or tangential) threshing drum or to an accelerator roller in the combine harvester.
A feederhouse assembly that operates in an undershot manner and has a rubber-fabric belt that comprises transversely arranged steel bars that engage with the crop has also been proposed (DE 10 2009 036 104 A1). The belt is likewise driven by the upper feederhouse roller, which is furnished with axially-extending cams, which engage between nubs on the inner side of the belt.
The conveyor must be tensioned sufficiently to guarantee a transmission of torque from the driven feederhouse roller to the chain conveyor and to prevent the chain from slipping over the nubs, particularly under a heavy load of crop on the feederhouse. In the prior art, feederhouses equipped with chains were tensioned by springs acting on the lower feederhouse roller, which guarantees a certain, sufficient pre-tension (DE 10 2004 036 183, U.S. Pat. No. 4,362,005), or by hydraulic cylinders (DE 199 25 691 A1, DE 10 2012 007 637 A1) or only by moving the lower feederhouse roller to a desired position and fixing it there (U.S. Pat. No. 2,858,012 A).
Because spring pre-tensioning of feederhouses having a rubber-fabric belt has the disadvantage that the tension is either not sufficient to prevent the cams of the belt from slipping on the driven feederhouse roller or must be so high that heavy wear on the belt results, it is necessary that the adjustable feederhouse roller in such feederhouses be locked in the correct position, analogously to U.S. Pat. No. 2,858,012 A, or the adjustable feederhouse roller must be prevented from approaching the other feederhouse roller any closer than a predetermined position. This correct position is determined on the basis of a measurement of the distances between the adjacent cams of the belt, which must then be converted into the target distance between the axes of rotation of the feederhouse rollers. This procedure is cumbersome, time-consuming and prone to error.
A problem addressed by the present invention is that of avoiding the aforementioned disadvantages.